Aircraft beam chord construction



Aug. 31, 1948. H. w. EARHART 448,362

AIRCRAFT BEAM CHORD CONSTRUCTION Filed sept. 26. 1945 l 'f BY Patented Aug. 31, 1948 UNITED STATES PATENT OFFICE AIRCRAFT BEAM CHORD CONSTRUCTION Harold W. Earhart, Wichita, Kans., assignor to Beech Aircraft Corporation, Wichita, Kans., a corporation of Delaware Application September 26, 1945, Serial No. 618,617

Claims. (Cl. 18S- 37) The inner, T-sections 9 are shown as made up each of two formed or extruded channel secticns I2, with their outer edge anges I3 set within and secured to the Side flanges lli of the outer with the bending moments at different points in channels by rivets and with their inner edge the length of the beam and to accomplish this in flanges I6 secured together coextensively and to a simple, practical way and With simple, easily the webV lil by rivets il. fabricated materials. These inner members may be made up each as Special objects are to enable the selection and a single extruded or otherwise formed T-shaped use of simple, flat strip laminations for the lo section, and it is contemplated also that these strength localizing elements and to confine and inner members may be made up each as a single restrain these from buckling by means contribchannel with opposite edge flanges secured withuting as well to the strength and formation oi in the opposite edge nanges of the outer chanthe chord. nels, without special provision ior attachment of Other desirable objects and the novel features l5 the web. In this latter event one or two beam of construction, combination and relation of parts Webs may be attached to either or both the legs by which the purposes of the invention are ator edge iianges of the outer channel section. tained will appear or are set forth in the follow- The laminations such as 6, l and 8, while us ing specification. ally and preferably of flat strips, may be icrmed The drawing accompanying and forming part in any suitable shape. These laminations are seof the specification illustrates a present practical lected and disposed,v according to number, to embodiment of the invention. Structure, howcarry the loads to which the beam is subjected ever, may be modified and changed in certain at different points. respects,v all within the true intent and scope of Figs. 1 and 2 illustrate a length of beam to the the invention as hereinafter dened and claimed. right of the center or mid-section and showing Fig. 1 in the drawing is a broken plan view of a the laminations of successively shorter length form of beam chord constituting the invention; toward the mid-portion of the beam. These may Fig. 2 is a broken side elevation, partly in be graded equally at top and bottom of the chord, section as taken on the plane of line 2-2 of as illustrated, or unequally at top and bottom, Fig. 3; 30 according to usual or special loading.

Fig. 3 is an enlarged vertical sectional view as The outer channel sections, inner T-sections on substantially the plane of line 3 3 of Fig. 2; and laminations disposed therebetween are con- Fig. 4 is a perspective and broken vertical secnected together and to each other by means of tional detail of the beam. rivets I8, bolts, welds or other fastenings. In the The invention involves n Special Combination illustration the rivets I8 extend through the outer of structural members including opposed channel channels, the laminations and the smaller chanelements 5 for the top and bottom chords, nat nels forming the inner T-sections. laminations such as S, l, 8, seated Within the As indicated in Figs. 1 and 2, the channels I2 channels and inner members 9, which may be of forming the heads 0f the T-SSCOHS may be T-section for tying the parts together and to the stepped as indicated at i9, 2li, 2l, to seat the web lil. successively shorter laminations. At the extreme The outer members 5 may be formed or eX- right in these views the T-section channel l2 is truded channel sections and these serve as bonds shown, in the absence of an interposed laminato unite all the members into a single unit. tion, directly engaging and secured to the outer These channels may be further formed for atchannel 5. tachment of other parts of the airframe. In the The outer channel sections and the inner T- illustration they are shown as having smooth, flat, sections being comparatively stiff against buckouter faces with inset shoulders Il at opposite ling failure, serve to provide buckling restraint edges providing seats for edges of skin panels for the nat laminations which make up the center and pads or anges to form hinge knuckles for portion of the beam chord and which in themattachment of other structural members, the latselves may have little or less stiffness against ter feature disclosed more particularly in cobuckling. The unit as a whole, therefore, has pending patent application Serial No. 565,713, great stiffness and strength, in those portions led November 29, 1944, now Patent No. 2,432,396, Where such qualities are required and without issued December 9, 1947.- special contouring or tapering of parts.

Laminations may be eliminated or added at any points considered necessary or desirable, enabling a beam chord to be fabricated to provide at any given point only the cross sectional area required to carry loads existing in the beam chord at such points. The shapes of the inner and outer members may remain constant or substantially so throughout the length of the beam, the load carrying capacity of the beam being varied through elimination or addition of simple, :dat strip lamin-ations. This eliminates any need for expensive extrusions, forgings, etc., orv expensive machining set-ups and operations heretofore required for varying the amount of materialin beam` chords of the solid type.

The combination and form of construction disclosed is particularly suitable for airplane` con,- struction involving less labor and material costs, loss in scrap and the like, existing in other modes of comparable construction.

What is claimedis:

1,. A beam for aircraft comprising a pair of chordsiconnec'ted by a web, said chords comprising outerchannels, T sections having'their heads secured in the channels andl their flanges secured to the web and superposed laminations of differ. ent length secured in the channels in. back of the heads of the T-sections.

2. A beam for aircraft comprisingv a pair ofv chords connected by a web, said chords. comprise ing outer channels, 'IT- sections having their heads` secured in the channels and their flanges secured.y

to the web and superposed laminatons of different length secured inthe channeis in back of the heads of the T-sections, the heads of said T-secftions havingI edge angessecured to the sides of said channels.

3. A beam. for aircraft comprising. ay pair, of chords connectedlby. a web, said chords comprising outer channels, 'l1-.sections having their heads securedl in the channels and their flanges secured to the web and superposed laminations of differ-v ent length secured in the channels in back of the heads of the T.se ctio ns, the T-sec'tions being SuC- cessively stepped to accommodate the different length laminations.

4. A beam for aircraft comprising a pair of chords connected by a web, said chords comprising outer channels, T-sections having their heads secured in the channels and their flanges Secured to the Web and superposed lami-nations of different length secured in the channels in back of the heads of the T-sections, theT-sections being successively stepped to accommodate the different length laminations and the channels being substantially straight to provide a beam of substantially uniform height.

5. A'beamfor aircraft comprising a pair of chordsconnectedwby a Web, said cords comprising opposed top andl bottom channels, laminations in superposedrelation in said channels and of different lengths proportioned to the loads imposed onthe beam at different points in the length of the same, said web being located between the channels and means securing the channels, laminations and web in the relation described, inc-lud@ ing inner channel members confining the laminations within said top and bottom channels and having side anges secured inside, the nanges of the top and bottom channels and provided with center flanges attached to the Web.

HAROLD W- EABHART.'

REFERENCES CITEDY The following references are of recordl in the file of this patent:

UNITED STATES PATENTS Number Name Date 184,521 Hammond Nov. 21, 1876 11,523,106 Dornier. J an.l 13,` 1925 1,636,902 Dewoitine July 26, 1927 1,846,367 Sikorsky Feb. 23, 1932 FORIEICJIS?` PATENTS Number Country Date 365,280 Great Britain Jan, 21, 1932i '715,869A France Dec. 1G, 1931` 

